Atomic beam tube apparatus with transverse headers and spacers to position the components in the housing



Oct. 17, 1967 I R. F. c. VESSOT 3,343,040

ATOMIC BEAM TUBE APPARATUS WITH TRANSVERSE HEADERS AND SPACERS TOPOSITION THE COMPONENTS IN THE HOUSING Filed July 2 1964 2 Sheets-Sheet1 an fx PRIIOR AR? INVENTOR. ROBERT F C. VESSQT ATTORNEY Oct. 17, 1967F. c. VESSOT 3,343,049

ATOMIC BEAM TUBE APPARATUS WITH TRANSVERSE HEADERS AND SPACERS TOPOSITION THE COMPONENTS Y IN THE HOUSING Filed July 27. 1964 2Sheets-Sheet 2 INVENTOR. ROBERT E C. VESSOT ATTORNEY United StatesPatent ABSTRACT OF THE DISCLOSURE An atomic beam tube with a circularelectric mode C- field resonator. The elements of the tube arecylindrical and mounted around a common-axis. Annular headers provide aself-jigging construction.

The present invention relates in general to atomic beam tubes and moreparticularly to an improved atomic beam tube utilizing a novel circularelectric mode C-field resonator and/ or a cylindrical self-jiggingconstruction whereby improved frequency stability is obtained and easeof fabrication facilitated. Such improved atomic beam tubes are useful,for example, as atomic clocks and as frequency standards.

Heretofore atomic beam tubes have employed the conventional Y-shapedC-field resonator formed of rec-.

tangular waveguide to provide a pair of axially spaced beam-fieldinteraction regions for exciting resonance of the atomic beam particles.A recent improvement in these cavities. involved feeding the RF. energyto the cavity through a low Q section and is described and claimed inU.S.' patent application Ser. No. 340,767 titled, .Improved CavityResonator for Atomic Resonant Devices, filed Ian. 28, 1964, inventorsJoseph H. Holloway-ct al.,

T0 POSITION,

circular electric cavity in this combination has many advantages overthe prior rectangular cavityresonator. For instance, the circularelectric mode'resonator allows use j of larger sized beam holes inthecavity'structure without as much coupling tothe dominant mode and thuswith, out producing as much phase shift in the RF. fields taken acrossthe beam in the beam field interaction region. Therefore, the transversephase shift is greatly reduced, leading to frequency stability which isin excess of 1 part. in 10 for cesium and leads to evengreater-enhance-Qment in stability of thallium beam tubes. In addition, the.. circularelectric mode resonator, when axially aligned with thebeam, path, lendsitself especially well to use. with quadrupole state-selecting ,beamfocusing "magnets, thereby permitting use of a higher number magnetic.poles leading to beams of higher flux density. Furthermore, be-. causeof the extremely low loss of the circular electric mode as compared toother modes, the undesired phase. shift of the RP. fields from onebeamrfieldinteraction. region to the next due to absorption of energy inthe side walls of the resonant structure is minimized, thus leading.

to enhanced frequency stability.

In another embodiment of the present invention.trans-'..

verse alignment of the various tube elements is readily obtained by atube construction wherein the tube elements I are supported fromtransverse headers inserted within a... self-jigging cylindrical barrelsupport member. Longi-.- 'tupdinal alignment is readily achieved by.theprovision.

. of spacer members inserted between the transverse headand assigned tothe same assignee as the present invention.

smaller dimensions of the rectangular guide for thallium relative tothe" transverse beam dimension. Inaddition, the local phase shiftsproduced by leakage of power out of the beam hole 'in the. rectangularguide'cavity is a significant phase shift factor and in the case ofthallium again creates a more severe limitation on maximum ob-,

tainable frequency stability because the beam hole is of relativelylarger size.

Another problem encountered with the prior atomic beam tubes is thatthey have employed a rigid longi-.

tudinal beam or channel member upon which the various tube elements aresupported. While this type of construction provides sufiicient rigidityit makes transverse align- One of the problems encountered in the priorrec-' ment of the tube elements difiicult because of the lack of a pairof orthogonal aligning surfaces. Also, suspension of the supportingchannel member presents certain difliculties in order to preventintroduction ,of stresses which would interfere with proper transversealignment of the parts with the beam over the elongated beam path. Sucha prior channel support structure is described and claimed in US. patentapplication No. 233,573 titled Atomic Beam Apparatus filed Oct. 29,1962, inventor Joseph H. Holloway et al., now issued as US. Patent3,323,008 and assigned to the same assignee as the present invention.

ers. The barrel support, in a preferred embodiment, also serves .as thevacuum envelope and is sealedat one end by a vacuum-tight electrical.socket or insulated feed-- through assembly.

The principal object of the provision of an improved atomic beam tube.

One feature of the'present inventionis the provision. of a circularelectric mode C-field resonator structure 2 whereby undesired phaseshifts in the applied 'R.F. fields in the beam-field interaction regionsare minimized and frequency stability of the atomic beam tube apparatusis enhanced.

Another feature is the same as the precedingfeature v wherein thecircular electric mode resonator is axially with the beam axis and aquadrupole 'or higher even numbered pole state selecting beam focusingmagnet is used, whereby the atomic beam density is increased and pfrequency stability enhanced.

Another feature of the present invention is the proi vision of an atomicbeam tube construction employing a barrel-shaped tube element supportingstructure with a plurality of axially spaced self-jigging transverseheader members mounted therein, said header member carrying therefromthe various tube elements whereby tube construction and alignment isgreatly facilitated.

Other features and advantages of the present invention will becomeapparent upon a perusal of the following specification taken inconnection with the accompanying drawings wherein:

a FIG. 1 is a longitudinal sectional view of an atomic: beam tubeemploying the features of the present invention;

FIG. 2 isfa line diagram showing the transverse magnetic field phaseshift variation over the beam for the prior art rectangular C-fieldcavity resonator;

i FIG. '3 is a line diagram showing the transverse R.F.i

magnetic field phase shift variation over the beam for the circularelectric mode C-field cavity resonator of the pres ent invention; p

Patented Oct. 17, 1967 present invention isthe 4 isan'enlar gedalongitudinal sectional view of a preferred C-.field cavity embodyingfeatures of the present invention;

FIG. 5 is a fragmentary perspective view of a portion of ,the structureof FIG. 4-delineated by line 55;

' ent invention. ,More specifically the atomic beam tube includes anelongated-combined tubular envelope andhollow cylindrical shaped supportstructure 2 as oIfn'on-magnetic stainless steel. The novel tubeconstruction will be more fully described below. Contained withinfhe'envelope 2 is a source 3 of atomic beam particles such as, forexample, cesium or thalium atoms which pro'jectsthe beam particlesaxially of the tube structure over an elongated beam path 4. A beamparticle detector 5 such as a conventional hot wire ionizer is disposed.at the terminal end of .theb'eam path for detectingresonance of thebeam.

A circular electric C-field cavity resonator 6 is disposed midwaybetween the beam source 3 and detector 5 for exciting atomic resonanceof the beam particles by an alternating magnetic field component H inthe presence of a DC. polarizing magnetic 'C-field component H When theatomic beam tube is being used as a frequency standard or *atomic clocthe beam particles are preferably resonated in a field independenttransition or resonance and for this condition the alternating R.-F.magnetic field H at the atomic resonance frequency should have a strongcomponent parallel to a DC. polarizing magnetic field-component Hcommonly called the C-field.

A particularly advantageous combination of C-field magnet and .C-fieldcavity resonator structure '6 is obtained when the circular electricmode resonator '6 is used with a cylindrical magnetically shieldedC-field solenoid 7 ,for producing the axially directed polarizingC-field H along the beam path within the resonator 6. The cylindricalsolenoid 7 yields a very uniform polarizing magnetic C-field and isdescribed and claimed in my copending U.S. patent application Ser. No.366,493 titled Atomic Resonance Method and Apparatus With ImprovedMagnetic Field Homogeneity Control filed May 1 l, 1964, inventorRobertF. -C. Vessot, and assigned to the same assignee as the presentinvention.

The'circular electric mode resonator structure 6 comprises a pair ofaxially spaced-apart cylindrical resonator chambers 8 coaxially alignedwith the beam path 4. Each cylindrical resonator 8 is provided with apair of apertures 9 the end walls -in registry with the beam path 4 topermit passage of the 'beam theret-hrough. An axially directed sectionof rectangular waveguide 11 interconnects the two cylindrical chambers 8and is coupled to each chamber 8 via the intermediary of 'ir-ises 12,see FIG. 3.

Wave energy is fed into the rectangular waveguide 11, at a pointpreferably midway of its length, via the intermediary of a suitablecoupling device, such as a conventional magnetic coupling loop 13, whichis excited by a coaxial line-'14. The rectangular section of guide '11preferably has high Q as taught in the first aforementioned ap-'plication Ser. No. 340,767. In addition, the coaxial line includes ahigh loss section 15 and a reflective discontinuity 16 disposed betweenthe high loss section and a source of microwave energy, not shown, atthe atomic resonance frequency connected at terminal 17 of the coaxialline 114. C-field resonator 6 structure is defined by the compositecoupled coaxial line sections, 15, 16 waveguide 11, and cylindricalchambers .8. The cylindrical chambers '8 are dimensioned to support adominant circularelectric- TE mode at the atomic resonance frequencywhen ex-.

cited with wave energy coupled through irises 12. The resonant sectionof transmission line or waveguidelh magnetic field across the beam,transverse phase and coupled chambers 8 define a high Q portion of thevcomposite resonator structure .6. The low .Q portion in cludes the highloss section 15 of coaxial line 14 intermediate the coupling loop 13 andthe reflective discon: tinuity to thereby provide a low Q compositeresonator to prevent thermal detuning-eifects while at the same timeproviding a high .Q portion to prevent undesired phase. shiftsbetween'the magnetic "fields in the spaced .charn-.

. bers 8 due to energy absorption in the high Q portion, as; I taught inthe aforementioned application 'Ser. No. 340,767.

The mounting of the shielded solenoid '7 and cavity structure 6 is morefully described below with .regard'to a preferred embodiment of thepresent invention shown in FIG. 4. r

A Pair of magnetically shielded state selecting magnets l 18 and 19 aredisposed .on opposite ends .of .the resonator structure 6, respectively.-In a preferred embodiment,

magnets 18and 19 are quadrupole orhexapole magnets to obtain a focusingof the beam as wellas state selectioml Magnet 18 is disposedbetween thesource 3 and the resonator 6. Magnet 18 focuses out of the beam atomicparticles of one energy state and focuses intoward the center of thebeam particles of the other energystate. Either state may be selectedfor the beam by merely intercepting the unwanted beam particles.However, by selecting the atomic energy state which .is focused intoward thecen ter of :the beam an additional advantage is obtained dueto' the increased beam density yielding smaller beam crosssectionalareas for a given beam flux intensity. Smaller beam cross-sectional arealeads ;to smaller transverse phase shifts in the applied RJF. resonatingmagnetic field 1 H in the beam-field interaction regions .and therebyyields greater frequency stability of the tube.

The :spaced resonator chambers 8 provide .the axially spaced beam-fieldinteraction regions for resonating the atomic beam particles. Theresonant fields H in :the spaced chambers .8, at atomic resonanceofthebeam, the particles out of phase*oper,ation, depending upon whethera ring detector of axially disposed button detector is used and alsodepending upon whether peak or null detection :is desired.

In the apparatus shown, for in phase? operation of chambers 8, at atomicresonance of the beam, the particles will .be deflected out of the beam:by the .second state selecting magnet 19. Thus, resonance of the beamwill appear as a null in the :detected beam current of detector 5 whenusing a button detector ,5 and a peak amplitude signal will :appear whenusing a ring or annular detector. If the phase of the RF. fields inchambers 8 is 180 out of phase (out of phase operation) .then,wi,th thebutton detector apparatus shown, at resonance there would be a peak inamplitude of the detected beam currentlat button detector :5 and a nullor minimum if an annular detector were utilized instead .of the "buttondetector.

The circular electric mode resonator structure 6 allows substantiallyless transverse phase shift in the applied R.F.

magnetic field 4 across the beam as compared :to the phase shift isillustrated in FIGS. 12 and 3. More .7

specifically FIGXZ shows the conventional rectangular waveguide and beamhole wherein the beam is directed across the guide from one broad wallto the other near the shorting end Wall of the cavity. Phase shift isproduced by flow ofpower to the lossy side walls of the cavity from thereflected wave. Thus, the phase shift increases in the direction of'travel of the reflected wave away from the shorting wall. This producesa phase shift'in the RF.

shift. One might think this phase shift could be reduced. byorienting-the beam hole such that it were elongated parallel to the:shorting wall such that the transverse.

to flow around the slot and thereby couples wave energy.

out through the beam hole and produces even greater phase shift.

' Referring now to FIG. 3 there is shown a similar diagram to that ofFIG. 2 showing the beam field interaction region and phase shift for acircular electric mode resonator chamber 8 and coaxial beam hole andtrajectory. In this instance the reflected wave travels axially of thechamber 8 and power loss in the side walls of the chamber is lessbecause the circular electric mode has the least power loss of any modeand certainly less than the rectangular waveguide mode. Furthermore,note that the phase shift is constant in any one of the transverseplanes of the cavity, such that the transverse phase shift across thebeam is negligible. What phase shift there is is longitudinal and itturns out that if this phase shift is equal in both chambers 8 and thechambers are symmetrical about a transverse plane midway betweenthe'chambers thatthe longitudinal phase shift will cancel out. Also thebeam holes do not significantly perturb the cavity circulating currents,since the currents are at a minimum in the end walls on the axis of theresonator chamber 8, as indicated, and circulate around the beam holerather than tending to flow across the holes. 1

In addition, the circular electric mode resonator is approximately twicethe diameter of the rectangular guide and can therefore tolerate a beamhole of approximately twice the size of the rectangular cavity for thesame perturbation. The circular electric mode resonator chamber 8 isespecially well suited for a thallium beam tube since the resonantfrequency for thallium is about twice that of cesium and therefore therectangular cavity would be about half the size of the cesium cavity.

Referring now to FIG. 4, there is shown a preferred circular electricmode cavity resonator structure 6 in corporating features of the presentinvention. The circular electric mode cavity in this instance is definedby a quartz cylinder 22 coaxially disposed of the beam path 4. Thecylinder is coated on the inside with a coating of low-loss conductingmaterial, such as silver, with a thickness of a few skin depths at theatomic resonance frequency. The end walls 23 of the cavity '6 are formedby conductive plates, as of aluminum, afiixed to the ends of the quartzcylinder 22 via the intermediary of flexible cylindrical segments 24, asof thin gauge BeCu. Annular recesses 25 are provided between the endwall and the cavity side wall to attenuate undesired TM modes that mightcouple to or interfere with the desired mode. a

A small diameter hollow dielectric tube 26, as of quartz, is coaxiallydisposed of the cylinder 22 and is coated at 27 over apreponderance ofits length on the exterior surface with a conductive material, such assilver, to produce an RF. field free region 28 within the interior ofthe tube 26. The conductive coating is terminated short of the endwalls23 at 29, such that the space remaining between points 29 and the endwalls 23 is dimensioned of sufficient length to support the TE circularelectric mode and permit the RF. magnetic fields of this mode to extendinto the beam path 4 in this region of the cavity structure 6, therebydefining the pair of axially spaced beam-field interaction regions 8.Regions 8 are coupled together by a resonant section of coaxialtransmission line 31 operating in a circular electric mode of the TEconfiguration, where n is greater than 1.

Wave energy is coupled into the circular electric mode resonatorstructure 6 via the intermediary of a shallow height section of arcuaterectangular waveguide 32 (See FIG. formed by conductive channel housingmember 33 strapped in electrical contact with the outer silvered surfaceof the quartz cylinder 22. A pair of conductive end walls 34 short theopposite ends of the rectangular waveguide 32. An axially-directedelongated coupling iris 35 is cut through and conductively platedthrough the Wall of the cylinder 22 for coupling to the circularelectric mode of the resonator 6 at a central point of symmetry. Asimilar iris 36 is cut through one of the end walls 34 of therectangular waveguide 32. A short arcuate section of waveguide 37interconnects the two irises and 36 for heavily coupling wave energytherebetween.

A pair of inductive vane members 38 produce a strong reflectivediscontinuity in the waveguide 32 and define a coupling iris 39therebetween and thus also define the outerterminal boundary of the feedarm portion of the cavity resonator structure 6. A resistor card 41 isdisposed across the feed arm portion of the guide 32 fom one broadwallto the other to heavily load the composite cavity resonator 6defined by the feed arm portion and the high- Q circular electric modeportions 31 and 8 to lower the composite Q of the entire resonatorstructure -6 without introducing loss into the high Q portion, therebyrendering the entire cavity relatively insensitive to thermal detuningeffects according to the teachings of the. aforementioned V patentapplication Ser. No. 340,767. Wave energy is coupled into the feed armwaveguide 32 via a coaxial line 42 and inductive coupling loop 43. Thecoaxial line 42 is directed axially of the tube'and is connected to asource of microwave power at the frequency of the atomic beam resonancedisposed externally of the tube 1. V

The cylindrical magnetically-shielded solenoid 7 (see FIG. 4) coaxiallysurrounds the cavity 6 and includes a cylindrical coil form 44, as ofaluminum, grooved on the outer surface and anodized to form aninsulative coating to receive multiple turns of aluminum wire 45formingthe C-field solenoid 7. A cylindrical magnetic shield member 46,as of a material sold by the Allegheny Ludlum Steel Corp. under thetrademark Moly Permaloy, coaxially surrounds the solenoid 7 to shieldthe interior of the solenoid from extraneously produced magnetic fieldsincluding-the earths field. A pair of centrally apertured annular.magnetically permeable end Walls 47 close off the ends of thecylindrical portion 46 of the solenoid shield. An outer cylindricalmagnetically permeable solenoid shield 48 coaxially surrounds the innershieldand likewise includes centrally apertured annular magneticallypermeable end closing walls 49. V

Referring now to FIGS.,1, 4, .6 and 7, circular electric mode cavitystructure 6 and the associated .solenoid 7 and magnetic shields are allsupported within the combined cylindrical vacuum envelope 2 and supportstructure in a self-jiggingmanner such as to readily achieve and main-.tain proper transverse alignment of the cavity structure 6 in thefollowingv manner: The cylindrical outer. 1'nag netic shield 48 isformed by a rolled sheet of metal and includes merely anoverlappingslidable. abutment of the axial marginal edge portions of theoutwardly tensioned cylinder 48. In this manner the .cylinder 48 is freeto expand out against theinner jiggingsurface of the inner bore of thecylindrical envelope 2, as of precision bore non-magnetic stainlesssteel tubing. A pair of annularheaders 51, as of stainless steel, jig tothe inside surface, of the cylindrical envelope 2 via the. intermediaryof the end port-ions of the outer cylindrical shield 48 and areaflixedthereto via a plurality of circumferentially spaced sheet metalscrews 52 threaded through av plurality of inwardly directed tabs 53.The screws also hold the end walls 49 of the shield to the side wallsofthe outer shield 48 via the tabs 53. v A 'The inner magnetic shield 46isindexed at itsends to the annular header 51 via the intermediary of apair of convoluted annular spacers 54, as of stainless steel. Thespacers 54 are welded to .the first header 51 and bear in longitudinaland transverse engagement against a pair of oppositely convolutedportions 55 of'the annular end walls 47 of the inner shield 46. I g Thecavity resonator structure 6 is indexed to and sup portedfrom the endsof the inner magnetic shields 47 via the intermediary of a pair ofdouble-convoluted annular spacers 56, as of aluminum. The annularspacers 56 index to transverse aligning interfaces 57 and 58 on theshield end walls 47 and cavity end walls 23, respectively. The centertube 26 for the cavity is supported from 7 and indexed to the cavity endwalls 23 via the intermediary of apair of annular headers 59. Theheaders 59 axial- 1y receive the tube 26 and capture same therebetweenby beating in longitudinal engagement against a pair of 'quartz washers.61 carried on the tube '26. i

The shielded cavity structure is fixedly secured against .axial movementto the envelope 2 substantially only at one end by having the outermagnetic shield 48 'fixed in the axial direction against stops 62spot-welded to the inside wall ofthe envelope 2 and to the shield 48. Ahelical spring '63 as of 'BeCu is captured at one end against the insidesurface of the magnetic shield end'wall 47 and a transverse corrugatedheader 65, as of aluminum, which provides transverse alignment but whichwill allow relative axial movement between the cavity 6 and the coilform 44.

The above-described self-jigging tube construction is especiallyadvantageous because the tube is made up of parts having greatlydiiferent coeflicients of thermal expansion and after assembly the tubeis evacuated and baked at 400 C. to fully outgas all parts. During thebakeout cycle the quartz cavity cylindrical side wall 22 expandsradially approximately 0.00 While the coil form 44 expands radiallyapproximately 0.130". Similarly, even greater differential expansionsare obtained in the axial direction. Proper transverse alignment toapproximately 0.001 .is required to be maintained after the bakeoutcycle over the length of the tube from source 3 to detector 5. The abovedescribed self-jigging construction permits the relatively largedifferential expansion while main- .taining the requisite 'concentricityor transverse alignment.

A similar self-jigging header and spacer support structure is employedfor the other elements of the tube structure, (see FIGS. 1, 6 and 7.)such as the source 3, state selecting magnets '18 .and 19, and detector5. While longitudinal spacing of the elements is not nearly so criticalas transverse alignment, proper longitudinal spacing is advantageouslyobtained by use of spacer ring members 66 or rods, not "shown, stackedin between successive selfjigging transverse headers 67. The entirestack of elements is then preferably spring-loaded in compression by acrenelated ring spring 68 disposed in between the stack of .elements andan end closing wall 69 of the envelope '2 which forces the elements downinto the support barrel against a suitable stop such as shoulder 70.Note, that if shoulder 70 is used, then stop 62 is eliminated. The endclosing wall 69 includes a lip portion 71 which abuts the envelope '2 atits open end'and is joined and .sealed thereto as by a Weld 72 runningaround the lip portion 71 at 72.

The end closing wall 69 includes a plurality of hermetically sealedfeedthrough insulator assemblies 73 for bringing in and out theelectrical connections for the various signals and potentials to variouselements within the tube. In addition, the end closing wall includes apinched-01f exhaust tubulation 74 for exhausting the tube duringprocessing. Moreover, the various transverse headers within the stack ofassembled elements are perforated at 75 to facilitate exhausting of thetube 1 during processing. The tube is pumped in use by means of aconventional getter ion pump assembly 76 (not sectioned) disposed withinthe stack of elements. Aligning pins 77 passing axially through alignedopenings in the transverse headers 67 and spacer rings 66 and serve toprevent torsional displacement of the variousparts'relative to eachother.

i The atomic resonance tube apparatus, previously :described, is notlimited to cesium or hydrogenatoms alone. Certain'other isotopes ofother metals such as, for example, thallium, and rubidium may be used.Any electron re-orientation transition or responance in atoms ormolemiles for .which the net at'oms or moleculesangular momentum, f, isan integer .in quantum units of Planks constant, It, may be used. Ingeneral, it iscontemplated any suitable molecular or atomic beam orassemblange having desired resonance characteristics may be used. Theterms atom or atomic particle as used herein'is defined to meanmolecules as well as atoms.

Since many changes could be made in the above construction and manyapparently widely dilferent embodiments of this invention could be madewithout departing frornthe scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense. Whatis claimed is:

1. An atomic beam jtube apparatus including means forming a source ofbeam particles for forming and projecting a beam of atomic particlesover a predetermined elongated beam path, means forming a detectordisposed along the beam path for detecting resonance of the beamparticles, means forming a pair of state selector magnets disposed alongthe beam path for deflecting the beam particles and selecting theirenergy states, means 'for applying microwave radiation to the beambetween said pair of state selector magnets for producing resonance ofthe beam particles, means forming an elongated tubular support structuresurrounding all of said aforementioned means for supporting same, andmeans forming a plurality of transverse headers, all of said supportedmeans being operatively supported from and deriving their axialalignment from said tubular support means via the intermediary of saidheader means, a plurality of said header means being axially movablerelative to said tubular support means to accommodate differential axialexpansion therebetween and to facilitate assembly of the'tubeapp'aratus, and means forming a plurality of spacer membersdisposed between adjacent transverse header means for determining theproper axial spacing of said supported means within the tube apparatus.

2. The apparatus according to claim 1 including means forming a springproducing an axially directed force holding together said supportedmeans and assuring proper longitudinal spacing thereof.

3. The apparatus according to claim 2 including means tor means mountedtherein for feeding different electric potentials to various meanswithin the tube apparatus.

4. The apparatus according to claim 1 wherein a plurality of said headermeans bear in slidable engagement at their outer periphery with theinside bore of said tubularsupport means for axially aligning saidsupported means within the tube apparatus.

References Cited UNITED STATES PATENTS 2,879,439 3/ 1959 Townes 33194 X2,972,115 2/ 1961 Zacharias et a1. 331-3 3,'()60,3 10/1962 LippS et -al.331-3 3,255,423 6/1966 Ramsey et al. 33-194 WILLIAM F. LINDQUIST,Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,548,040 October 17, 1967 Robert F. C. Vessot It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

Column 4, line 37, strike out "at atomic resonance of the beam, theparticles" and insert instead may be selected for "in phase" operationor Signed and sealed this 22nd day of October 1968.

(SEAL) Attest:

Edward M. Fletcher, Jr. EDWARD BRENNER Attesting Officer Commissioner ofPatents

1. AN ATOMIC BEAM TUBE APPARATUS INCLUDING MEANS FORMING A SOURCE OFBEAM PARTICLES FOR FORMING AND PROJECTING A BEAM OF ATOMIC PARTICLESOVER A PREDETERMINED ELONGATED BEAM PATH, MEANS FORMING A DETECTORDISPOSED ALONG THE BEAM PATH FOR DETECTING RESONANCE OF THE BEAMPARTICLES, MEANS FORMING A PAIR OF STATE SELECTOR MAGNETS DISPOSED ALONGTHE BEAM PATH FOR DEFLECTING THE BEAM PARTICLES AND SELECTING THEIRENERGY STATES, MEANS FOR APPLYING MICROWAVE RADIATION TO THE BEAMBETWEEN SAID PAIR OF STATE SELECTOR MAGNETS FOR PRODUCING RESONANCE OFTHE BEAM PARTICLES, MEANS FORMING AN ELONGATED TUBULAR SUPPORT STRUCTURESURROUNDING ALL OF SAID AFOREMENTIONED MEANS FOR SUPPORTING SAME, ANDMEANS FORMING A PLURALITY OF TRANSVERSE HEADERS, ALL OF SAID SUPPORTEDMEANS BEING OPERATIVELY SUPPORTED FROM AND DERIVING THEIR AXIALALIGNMENT FROM SAID TUBULAR SUPPORT MEANS VIA THE INTERMEDIARY OF SAIDHEADER MEANS, A PLURALITY OF SAID HEADER MEANS BEING AXIALLY MOVABLERELATIVE TO SAID TUBULAR SUPPORT MEANS TO ACCOMODATE DIFFERENTIAL AXIALEXPANSION THEREBETWEEN AND TO FACILITATE ASSEMBLY OF THE TUBE APPARATUS,AND MEANS FORMING A PLURALITY OF SPACER MEMBERS DISPOSED BETWEENADJACENT TRANSVERSE HEADER MEANS FOR DETERMINING THE PROPER AXIALSPACING OF SAID SUPPORTED MEANS WITHIN THE TUBE APPARATUS.